Ensure modules for autoreload have a __loader__ attribute.

IPython/extensions/autoreload.py

@@ -372,6 +372,7 b' def superreload(module, reload=reload, old_objects={}):'
         old_name = module.__name__
         module.__dict__.clear()
         module.__dict__['__name__'] = old_name
+        module.__dict__['__loader__'] = old_dict['__loader__']
     except (TypeError, AttributeError, KeyError):
         pass